kuecks

> I also ran into the issue of `Option` versus `Pin` and also of `Option` in that PR (`Pin` is allowed today and normalizes to just `Pin`); so make sure...

Notes: all the changes under demo/ will be reverted, that's just my playground. The code feels quire repetitive and nasty, but I can't figure out any better way, there's just...

@djpiper28 yes I am still interested in pushing this through, I think dtolnay is (understandably) just quite busy unfortunately. I may explore alternative implementations, specifically reference_wrapper, in the meantime